The present invention relates to infrared radiometry and more particularly to non-contact temperature measuring apparatus which is relatively insensitive to the surface characteristics of the target whose temperature is being measured.
As is understood by those skilled in the art, the use of radiometric techniques for the non-contact measurement of temperatures has typically required that the instrument be designed for a particular application, taking into consideration not only the temperature range in which measurements are to be taken, but also the nature of the target and particularly its surface characteristics. As is understood, few products under manufacture conform with the ideal black body situation and emissivity and transparencies vary over wide ranges and with wavelength. Extreme examples include measuring the temperature of polished aluminum or of thin plastic films.
It has been particularly difficult to design instruments which will measure the temperature of a target without being significantly affected by surface characteristics which can vary widely even though basic identity of the target is the same. One example of such an application is the temperature measurement of aluminum ingots where the surface may be anywhere from bright to highly tarnished and coated with miscellaneous contaminants.
Among the several objects of the present invention, it may be noted the provision of a highly accurate non-contact temperature measuring device; the provision of such a device which is operable over a wide range of target temperatures; the provision of such a device which is relatively insensitive to surface characteristics of the target whose temperature is to be measured; the provision of such a device which is relatively insensitive to changes in emissivity; the provision of such a device which is relatively insensitive to surface contaminants on the target; the provision of such a device which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.